Specs:
‘87 Trans Am, LG4 4bbl Carb. (E4ME?) 700R4 auto.

Ok, there’s a lot of stuff I have done lately, half of which I won’t remember to include in this post…

My car runs REALLY rough. Sounds like it isn’t running on all cylinders. Sounds like a tugboat; Really deep and airy / bubbly. The whole car shakes violently at idle. RPMS are at 500 in gear, which is where it usually is.

When I let my foot off the brake the car, eh, shakes or rather pulls back and forth until I apply some gas. Also, I have to apply quite a bit more gas to get her going from a red light.

This is what I have done in the past 6 months or so:
- Changed carb. (Replaced it with a rebuilt E4ME from Autobone)
- Changed spark plugs and wires
- Changed to an 160* Thermostat
- Changed air and fuel filter
- Changed the normal stuff, coolant, oil, etc

The car has been running “better than new” for the past 3 months or so. It’s been pretty sweet actually. As mush fun as you can have with an LG4, that’s for sure

This problem occurred overnight. I left it standing outside for 2 days in 40* weather (coldest temp at night) @ 7000 ft. Don’t know if that has anything to do with it, but could it be my cat that went south? Fuel pumping going? I was able to drive her home (90 miles) so I doubt it’s a fuel delivery problem. My dad said that it sounded like it wasn’t firing on all cylinders. I tried removing one wire at a time to see if I could hear any change, which I couldn’t…

Next day: Started the car up and saw a puff of white smoke come out of the exhaust. Ok, prolly condensation or something. No biggie. I let it run for 10 minutes or so. Came back 30 mins later (about 70-75* outside) and started her up again. White smoke AGAIN, and an unpleasant smell from the exhaust… Running rich…?

I’m stumped. And ideas?

 

Pull your plugs and see if they are wet. White smoke could be an indication of water in the cylinders, possibly a blown head gasket, especally with you needing to apply more gas to keep it running at a red light.

 

The fact that it happenned all at once makes me think it could be the computer. I am assuming you have a computer on that car.

 

a computer wont make a car smoke white in 70 degree weather, white smoke and the smell your saying is burning coolant, check your spark plugs as mentioned, your intake gaskets are leaking or you have a blown head gasket, cracked head or block...

 

Thanks for the help guys! :lala:

It seems like I have a couple of different (perhaps unrelated?) problems. Anywho, this is what I have done so far: (Man this post is gonna be long, sorry guys)

Changed plugs again! I pulled a couple of plugs and they all were showing signs of my car running rich. I put these puppies in 3 months ago and they were already pitch black, and to an untrained eye almost looked rusty, or at least were a tad brown.
Also, I did find *some* oil on the plugs, but it was on/along the threads, not actually on the tip (right terminology?)

I'm a complete newbie at this (as if you didn’t know) but since there wasn't any oil on the tips, it most likely has something to do with valve seals, and not rings... Right?

Also, I temporarily took off the cat and put a straight pipe in its place and that seemed to help quite a bit. The cat was VERY hot, but not glowing. I didn't hear a rattle from it, but when I looked inside the cat I could clearly see that it needed to be replaced. It has 103.xxx miles on it, and the car has been running way too rich for the past two years (at least). My car still seemed a bit sluggish, but I figured that it probably had something to do with not having a cat, A.I.R. tubes still open, computer freaking out, etc…

So this is what I have done (or will be doing)

Replaced cat. (Should arrive on Wed or Thu, 2 more days without the Zam)
Changed oil and filter
Replaced O2 sensor
Cleaned air filter (K&N)

Anything else I should think of?

BTW, the white puff of smoke at startup is now gone. There is still an unpleasant smell though. I can't really tell if it's the same smell or not. But I'm assuming it's there because I took the cat off.

Again, thanks for your help guys! :rockon:

 

Forgot to mention a "tiny" detail. The engine (LG4) was replaced by a previous owner. That obviously doesn't automatically rule out blown head gasket, or cracked head/block, but hopefully the person who built this engine wasn't a complete idiot and it should hold up for more than 30.000 miles....?

 

Forsete,

When you replacecd the carburetor and set the mixture control solenoid and TPS (you DID set those, right?) what was the final TPS voltage and M/C solenoid duty cycle (dwell reading)?

 

you mentioned 7000 feet of altitude. that is well over a mile above sea level. when you put all these parts on, did you tune it to the elevation that you drive at? if the car was running fine at your normal altitude and only started acting up after you went up, i would suspect ignition. too much fuel could foul your plugs. fould plugs could also damage your cap as the spark is pretty desperate to get to any ground it can. i'm not too positive about the ability of the electronic carb to make adjustments though, so i would appreciate it if someone would step in and confirm what i said.
jess

 

First of all, everything seems to be ok now! :lala:

I decided to change everything I could think of as far as tune-up goes. And I'm glad I did. When I took off the distributor cap the thingies (I think that's the scientific term for them) were all covered in that white, powdery ashy stuff that you see on plugs. I'm amazed that this car even started.
Anyway, I think that's were most of the problem was, besides a clogged cat.

As for the carb, all I did was slap it on and adjusted the choke and idle. I thought the computer took care of the rest (well, most of it)

Anyway, I went to get some gas and let the engine warm up. Then I went out and floored it at different speeds/gears and man that LG4 can really be fast when it's in good shape! It feels like I gained 20-30 hp. (which I obviously didn't)

Thanks for all the help guys! :hail: I think I just fell in love with that slow @$$ piece of manure again! Oh wait, it's not THAT slow anymore!